Towards gas sensing with vertically aligned carbon nanotubes interrogated by THz radiation pulses

When vertically aligned carbon nanotubes (VACNT) are exposed to gases, their dielectric properties may change by mechanisms such as doping effects or a modification of the scattering channels of the mobile charge carriers of the VACNT. This report provides first data of a study which aims at an exploration of such conductivity changes in the THz frequency regime. The test gases are NH 3 and SO 2 which are known to act as donors, respectively as acceptors when interacting with the carbon nanotubes. Our measurements confirm the doping effects. This may open the way towards gas sensors based on the VACNT interrogated by THz radiation, where the VACNTs act as an accumulation volume for certain species contained in a gas stream.